[emacs] Add snippets for latex mode.

.emacs.d/snippets/latex-mode/matrix.yasnippet

@@ -0,0 +1,11 @@
+# -*- mode: snippet -*-
+# contributor: Song Qiang <tsiangsung@gmail.com>
+# key: matrix
+# group: math
+# name: \begin{matrix} ... \end{}
+# --
+\begin{${1:$$(yas/choose-value '("pmatrix" "bmatrix" "Bmatrix" "vmatrix" "Vmatrix" "smallmatrix"))}}
+\label{${2:"waiting for reftex-label call..."$(unless yas/modified-p (reftex-label nil 'dont-insert))}}
+$0
+\end{$1}
+